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The D-S action was first described just one year ago in arXiv0802.0864.

Page 3 "...The reader might wonder at this point whether (6) is a discretization of a continuum action for GR, like Regge’s is a discretization of the Einstein-Hilbert action ∫√gR. We argue that this is the case, the continuum avatar of (6) being Plebanski’s action [8]."

The most recent use of the new action was in December 2008, in the third of a series of papers by Rovelli and others,

Page 4 "...S (j, n) is the Regge action [19] of such a geometrical

4-simplex (more precisely, the Dittrich-Speziale action [20]), divided by 8π[itex]\hbar[/itex]G

More about this later.

Speziale was one of Rovelli's students and then postdoc at Perimeter for several years ( http://www.perimeterinstitute.ca/personal/sspeziale/ ) and now fills a permanent faculty position at Marseille.

Dittrich did her Diplomarbeit with Loll, was at Berlin or Potsdam for a while, postdoc at Perimeter, and is now at Utrecht.

Trivia: since we say tetrahedron for 3-simplex, it would be correct to call the 4-simplex a pentachoron.

Page 3 "...The reader might wonder at this point whether (6) is a discretization of a continuum action for GR, like Regge’s is a discretization of the Einstein-Hilbert action ∫√gR. We argue that this is the case, the continuum avatar of (6) being Plebanski’s action [8]."

The most recent use of the new action was in December 2008, in the third of a series of papers by Rovelli and others,

**LQG propagator: III. The new vertex**, arXiv0812.5018.Page 4 "...S (j, n) is the Regge action [19] of such a geometrical

4-simplex (more precisely, the Dittrich-Speziale action [20]), divided by 8π[itex]\hbar[/itex]G

_{Newton}."More about this later.

Speziale was one of Rovelli's students and then postdoc at Perimeter for several years ( http://www.perimeterinstitute.ca/personal/sspeziale/ ) and now fills a permanent faculty position at Marseille.

Dittrich did her Diplomarbeit with Loll, was at Berlin or Potsdam for a while, postdoc at Perimeter, and is now at Utrecht.

Trivia: since we say tetrahedron for 3-simplex, it would be correct to call the 4-simplex a pentachoron.

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